Does the Greenhouse Gas (GHG) Protocol say a carbon dioxide (CO2) factor per unit of heat is more accurate than a per-litre or per-kilogram factor for fuel?

Yes, with one exception. The GHG Protocol Corporate Standard says published fuel factors based on energy content are generally more accurate than mass or volume ones, unless measured at your own site. Per tonne, Intergovernmental Panel on Climate Change (IPCC) defaults give 2,441 kilograms of CO2 for other bituminous coal and 1,202 for lignite.

What the Corporate Standard says

• For fuel consumption, published emission factors based on fuel energy content are generally more accurate than those based on mass or volume, except when the mass or volume factors have been measured at company or site level.
• Convert fuel consumption data to energy units before applying carbon content emission factors, which may be better correlated to a fuel's energy content than its mass.
• Differences between measured and default values need to be qualitatively explained and justified from the company's operations.

How the energy route works

1. Quantity bought, in tonnes, times the fuel's net calorific value (NCV), which is its heat per tonne. IPCC prints NCV in terajoules (TJ) per gigagram (Gg), and 1 TJ per Gg is the same as 1 gigajoule (GJ) per tonne.
2. Energy, in GJ, times the CO2 factor per GJ. IPCC prints that factor in kilograms per TJ, so 74,100 is 74.1 kilograms per GJ.
3. IPCC builds its factor as carbon content times oxidation factor times 44/12, which is the weight ratio of CO2 to carbon.

Why per-tonne factors differ so much between coals

Per GJ, IPCC's defaults sit in a narrow band: 94.6 kilograms for other bituminous coal, 96.1 for sub-bituminous coal and 101.0 for lignite. But a tonne of lignite holds far less heat than a tonne of bituminous coal, so per tonne the CO2 differs by half. A per-tonne factor silently carries a heat value. Using one for the wrong grade of coal gives a wrong answer even if the arithmetic is right.

The same logic covers a per-litre factor. Working back from IPCC's 74.1 kilograms per GJ for gas or diesel oil, a diesel factor of 2.645 kilograms per litre implies about 35.7 megajoules per litre, and with IPCC's 43.0 megajoules per kilogram about 0.830 kilograms per litre. That is my arithmetic, not a figure either source prints. It shows that any per-litre or per-tonne factor holds a heat value and a density inside it.

Where the heat value is least certain

• IPCC's Table 1.2 gives 95% limits around each default NCV: gas or diesel oil 41.4 to 43.3, other bituminous coal 19.9 to 30.5, and lignite 5.50 to 21.6 TJ per Gg.
• So diesel's heat value is tight, and coal's is not. My reading: for coal, a supplier or laboratory heat value for your own purchases is better evidence than a default. The Standard lets you use factors measured at your own site, and a lab carbon and heat value is one way to measure one.

What to keep for a verifier

• The unit of the factor (per GJ, per tonne or per litre) and where it came from.
• If the factor is per tonne or per litre, the heat value it assumes, or a note that it was measured at your site.
• Any gap between a measured figure and a default, with the reason.

One tonne of fuel, IPCC defaults

• Gas or diesel oil: 43.0 GJ x 74.1 kilograms (kg) per GJ = 3,186.3 kg CO2
• Other bituminous coal: 25.8 GJ x 94.6 = 2,440.7 kg
• Sub-bituminous coal: 18.9 GJ x 96.1 = 1,816.3 kg
• Lignite: 11.9 GJ x 101.0 = 1,201.9 kg
• Per GJ the four run from 74.1 to 101.0 kg. Per tonne they run from 1,201.9 to 3,186.3 kg
• Lignite against other bituminous coal, per tonne: 1,201.9 / 2,440.7 = 0.492, so 50.8% less

IPCC 2006 default NCVs (Table 1.2) and default CO2 factors (Table 1.4) for the fuel types named. A given Indian coal grade may differ from these defaults; use a test or supplier heat value where you have one. IPCC does not use Scopes.

What Senseible does here

Senseible reads fuel invoices and electricity bills into monthly records, so the litres or tonnes you bought are on file for whichever factor you and your verifier agree.

• Which IPCC coal line fits my coal
• IPCC default calorific values in kcal per kg
• IPCC 95% range around default fuel factors
• Which emission factor to prefer in India
• Free calculators

Sources: GHG Protocol Corporate Accounting and Reporting Standard (revised edition), chapter 7 (emission factors, activity data measures), IPCC 2006 Guidelines, Volume 2, Chapter 1 (Tables 1.2 and 1.4)

Last reviewed 2026-11-05. Factors are IPCC 2006 defaults for the named fuel types, not Indian grades. Check your own fuel supplier's heat value before you rely on a coal factor.